In order to study the possible role of the p44/42 mitogenactivated protein kinases(MAPK) and the signal transducer and activator of transcription 3 (STAT3) in the cancerization process of leukemia marrow cell induced by γ-ray irradiation, the mice were divided into three groups according to the pathological examination: the carcinomatous group, the uncarcinomatous control group and the unirradiated control group. The level of phospho-STAT3 were detected by the immunoprecipitation and Western blotting assay, and the change of the expression of the P44/42 MAPK, phospho-P44/42 MAPK and STAT3 were detected by Western blotting analysis. The results showed that the levels of P44/42 MAPK and phospho-P44/42 MAPK were significantly higher in the marrow cell of the carcinomatous group than that in the control groups (P＜0.05) respectively. But statistically, there was no difference in the levels of STAT3 and phospho-STAT3 among the three groups (P＞0.05). All the results suggest that there is a possible involvement of Ras/ P44/42 MAPK pathways in the cancerization process of leukemia cell, while JAK/STAT3 pathway makes no contribution to the process of radiation carcinogenesis.